Influence of thread parameters on the withdrawal capacity of wood screws to optimize the thread geometry

Abstract For wood screw connections, the withdrawal capacity is essential and therefore an optimization target for screws. The based on composite action between thread wood. Optimizing geometry requires knowledge of how parameters influence capacity. Up to now, this largely unknown. Therefore, objective determine height (1 mm; 1.48 mm), flank distance (3.04 6.08 lead angle (6.8°; 13.6°), (30°; 55°) influences are investigated a tangential screw-in direction in spruce. this, flat ribbed bars, so-called threaded test objects, used. effect measured using experimental setup standard EN 1382 two different planes fiber. 242 tests RT plane 286 TL were analyzed with multifactorial analyses variance. height, distance, show significant effects both planes. A larger smaller pitch, more acute increase Only plane, shows higher determined can be used design screws capacities. accuracy calculation models connections also improved findings. With results, confirmation could found known theory compression cones explaining angle.